--          This file is part of SmallEiffel The GNU Eiffel Compiler.
--          Copyright (C) 1994-98 LORIA - UHP - CRIN - INRIA - FRANCE
--            Dominique COLNET and Suzanne COLLIN - colnet@loria.fr 
--                       http://www.loria.fr/SmallEiffel
-- SmallEiffel is  free  software;  you can  redistribute it and/or modify it 
-- under the terms of the GNU General Public License as published by the Free
-- Software  Foundation;  either  version  2, or (at your option)  any  later 
-- version. SmallEiffel is distributed in the hope that it will be useful,but
-- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-- or  FITNESS FOR A PARTICULAR PURPOSE.   See the GNU General Public License 
-- for  more  details.  You  should  have  received a copy of the GNU General 
-- Public  License  along  with  SmallEiffel;  see the file COPYING.  If not,
-- write to the  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-- Boston, MA 02111-1307, USA.
--
class IFTHEN
--
-- Note : it is not really a complete Eiffel INSTRUCTION. 
-- It is just a small part of an IFTHENELSE. 
--

inherit IF_GLOBALS;

creation make
   
feature 
   
   expression: EXPRESSION;
   
   then_compound: COMPOUND;
     -- Not Void if any.
     
   run_compound: COMPOUND;
	 -- Not Void when instruction is checked for.

feature {NONE}

   point2: INTEGER;
	 -- To reach the end of IFTHENELSE.

feature 
   
   make(exp: like expression; tc: like then_compound) is
      require
	 exp /= void;
      do
	 expression := exp;
	 then_compound := tc;
      ensure      
      	 expression = exp;
	 then_compound = tc;
      end;

feature {IFTHENLIST}

   afd_check is
      do
	 expression.afd_check;
	 if then_compound /= Void then
	    then_compound.afd_check;
	 end;
      end;

feature
   
   current_type: TYPE is
      do
	 Result := run_compound.current_type;
      end;
   
   compile_to_c(need_else: BOOLEAN): INTEGER is
      local
      	 trace: BOOLEAN;
      do
	 if expression.is_static then
	    cpp.incr_static_expression_count;
	    if expression.static_value = 1 then
	       print_else(need_else); 
	       cpp.put_string("{/*AT*/");
	       if then_compound /= Void then
		  then_compound.compile_to_c;
	       end;
	       cpp.put_string("}%N");
	       Result := static_true;
	    else
	       cpp.put_string("/*AF*/");
	       Result := static_false;
	    end;
	 else
	    Result := non_static;
	    trace := not expression.c_simple and then run_control.no_check;
	    print_else(need_else); 
	    cpp.put_string("if (");
	    if trace then
	       cpp.trace_boolean_expression(expression);
	    else
	       expression.compile_to_c;
	    end;
	    cpp.put_string(") {%N");
	    if then_compound /= Void then
	       then_compound.compile_to_c;
	    end;
	    cpp.put_string("}%N");
	 end;
      end;
   
   compile_to_jvm: INTEGER is
      local
	 point1: INTEGER;
      do
	 if expression.is_static then
	    jvm.incr_static_expression_count;
	    if expression.static_value = 1 then
	       if then_compound /= Void then
		  then_compound.compile_to_jvm;
	       end;
	       Result := static_true;
	    else
	       Result := static_false;
	    end;
	 else
	    Result := non_static;
	    point1 := expression.jvm_branch_if_false;
	    if then_compound /= Void then
	       then_compound.compile_to_jvm;
	    end;
	    point2 := code_attribute.opcode_goto;
	    code_attribute.resolve_u2_branch(point1);
	 end;
      ensure
	 (<<static_true,static_false,non_static>>).fast_has(Result)
      end;
   
   compile_to_jvm_resolve_branch: INTEGER is
      do
	 if expression.is_static then
	    if expression.static_value = 1 then
	       Result := static_true;
	    else
	       Result := static_false;
	    end;
	 else
	    Result := non_static;
	    if point2 > 0 then
	       code_attribute.resolve_u2_branch(point2);
	    end;
	 end;
      ensure
	 (<<static_true,static_false,non_static>>).fast_has(Result)
      end;

   use_current: BOOLEAN is
      do
	 Result := expression.use_current;
	 if not Result and then then_compound /= Void then
	    Result := then_compound.use_current;
	 end;
      end;
   
   start_position: POSITION is
      do
	 Result := expression.start_position;
      end;
      
   pretty_print is
      do
	 fmt.level_incr;
	 fmt.set_semi_colon_flag(false);
	 expression.pretty_print;
	 fmt.level_decr;
	 fmt.keyword("then");
	 fmt.indent;
	 if then_compound /= Void then
	    then_compound.pretty_print;
	 end;
      end;
   
   to_runnable(rc: COMPOUND): like Current is
      local 
	 e: like expression;
	 tc: like then_compound;
	 t: TYPE;
      do
	 if run_compound = Void then
	    run_compound := rc;
	    e := expression.to_runnable(current_type)
	    if e = Void then
	       error(expression.start_position,
		     "Bad BOOLEAN expression.");
	    else
	       expression := e;
	       t := expression.result_type;
	       if not t.is_boolean then
		  eh.append("Expression of if/elseif must be BOOLEAN. ");
		  eh.add_type(expression.result_type,fz_is_not_boolean);
		  eh.add_position(expression.start_position);
		  eh.print_as_error;
	       end;
	    end;
	    if then_compound /= Void then
	       tc := then_compound.to_runnable(current_type);
	       if tc /= Void then
		  then_compound := tc;
	       end;
	    end;
	    if nb_errors = 0 then
	       Result := Current;
	    end;
	 else
	    !!Result.make(expression,then_compound);
	    Result := Result.to_runnable(rc);
	 end;
      end;
   
feature {NONE}
   
   print_else(need_else: BOOLEAN) is
      do
	 if need_else then
	    cpp.put_string(" else ");
	 end;
      end;
   
invariant
   
   expression /= Void;
   
end -- IFTHEN